Control apparatus



' Oct. 17, 1933.

-W. G. COOK CONTROL APPARATUS 5 Sheets-Sheet 1 Filed March 17, 1930 08 9 9 3 5 w I 7 o 5 A 6 m a n m w n w B I 6 2 l||| I 5 m E A f M f R/l I71 H R a 31 8 5L 1 3 a 7 m M 5 8 I rm nwA I z 9 7 5 I wA A J n m m M 9 m w J 2 m 1 1 m 3 5 I 0 9 f B 3 3 .m I 3 x 7 A u/ 6 g A An \IG N m I 5 0 3- 5 A m 4 s m Q INVENTOR M'l/ard 6. Cook ATTORNEY Oct. 17, 1933. G COOK 1,930,509

CONTROL APPARATUS Filed March 17, 1950 5 Sheets-Sheet 5 INVENTOR Mi/lard G Cook BY I I I ATT ORNEY Oct. 17, 1933. w. G. COOK CPNTROL APPARATUS Filed March 17, 1950 5 Sheets-Sheet 4 2 W m: m 7 6 5 3 All I 7 9 2 w 5 m 7 m /L m. 6 un R w 0 6 v w :l L w F21 I y 3 &w \W 3 l 4 9 W W unit a m w 2 H o 8 6 I 6 A INVENTOR Willard C 00k ATTORNEY Oct. 17, 1933.

w. G. cooK CONTROL APPARATUS Filed March 17,1930 5 Sheets-Sheet 5 INVENTOR Willard G Coal Y ATHTORNEY Patented Oct. 17, 1933 CONTROL APPARATUS Willard G. Cook, Forest Hills, Wilkinsburg, 'Pa.,

assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Application March 17, 1930. Serial No. 436,317" 22 Claims. (01. 172-179) I My invention relates to control apparatus and more particularly to a time-limit reversing control system for reversing motors such as are used to drive rolling mill tables or similar reciprocating devices.

One object of my invention is to provide for controlling the time of reversal of a reversing motor. M

More specific objects of my invention are, to provide forlimiting the current flowing through a motor, at the instant of the reversal of the connections while the motor is rotating in a given direction, i. e., during plugging, to a value tmprevent damage to the motor and to provide for controlling the period of reversal of the niotor during plugging as a function of the counterelectromotive force of the motor, the counterelectromotive force of the motor and a definite interval of time, or a definite interval of time only, as desired.

A further object of my invention is to provid a system of control for a reversing motor that shall be, simple and eiiicient in operation, comparatively inexpensive and easy of manufacture in view of the relatively few parts required, and which may be readily applied to a reversing motor. I e

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both. as to its organization and its method. of operation, together with additional objects and advantages thereof, will best be understood from the following description of specifie-embodiments when read in connection with the accompanying drawings, in which:

Figure 1 shows diagrammatically a revers ing control system wherein the time of reversal is determined by the inertia of the load;

Figs. ,2 and 3 show diagrammatically modifications of the reversing control system wherein the time of reversal is controlled by time limit devices.

Figs. 4 and 5 show diagrammatically modifications of the reversing control system wherein the time of reversal is controlled according to the inertia of the load and time limit devices.

In the following discussion, corresponding reference characters refer to corresponding parts in all the'modiflcations shown, and different ref-- erence characters are .used only for the different modifications when the elements referred" entirely different functions in different modifications. 1

Referring more particularly to Fig. 1 of the drawings, land 2 designate the positive and negative line conductors of a source of power, and 6 designates a motor for driving a reciprocating device. The directional contactors are designated by 3' and 4; and'lhas reference to a starting resistor having resistor sections 54, 55 and 56 controlled by a plurality of short circuiting switches or accelerating relays, which are inturn controlled by a'pair of time-limit relays 14 and 15. The entire control system is controlled by a manual controller 10. A polarized plugging relay 108 responsive to the counterelectromotive force of the motor is provided and thus controls the time of the plugging operation according to the inertia/of the load driven by the motor 6.

Assuming that lines 1 and 2 are not energized, then the various elements hold the position shownin Fig.1. If the switch (not shown) in the lines 1 and 2 be closed and the controller 10 be in the off position, then a circuit is established from the positive line 1 through conductor 16, polarizing coil 123 of plugging relay' 108, conductors 124 and 21 to the negative line 2. In parallel circuit relation to the polarizing 0011123 is disposed a' resistor 20, neutral;- izing coil 18 of the time limit relay 14, neutralizing coil 19 of the time limit relay l5 and conductor 21 to the negative line 2. Polarizing coil 123 alone is not sufliciently strong to cause movement of contactlll to engage with either of the contacts 110 or 112. Movement of the controller 10 to the first forward position establishes a circuit from the positive line 1 through conductor 30, contact fingers 64 and 67, bridged by the connected controller segments 36 and 38, conductor 41, actuating coil 42 of directional contactor 3, conductors 28 and 29, actuating coil 40 of the line contactor 5 to the negative line 2. Energization of actuating coils 42 and 40 of the directional contactor 3 and line contactor 5 respectively, causes the closing of the contacts associated with contactors 3 and 5. A motor circuit is thereby established" from the positive line 1, contacts 43, bridged by the interlock 44, conductor 45, armature 46 of the motor 6, conductors 4'7 and 48, contacts 49, 105 bridged by bridgingmember 50, conductor 51, series field winding 52, and -the startingresistor sections 54, 55 and 56, conductor 57, contacts 58, bridged by the bridging member 59 to the negative line 2. Connectedacross the armature 10 terminals is a circuit through conductor 60, movable actuating coil 61, of the polarized plugging relay 108, and conductor 162.

When the controller stands in the first for- 5 ward position regardless of whether the motor starts rotating or not, the resistance drop across the armature 'is suilicient to cause movement or the contact 111 0! the polarized relay 108 to establish a circuit through contacts 110 and 111. Furthermore, since the voltage is applied to the starting resistor 7, the drop across the resistor sections 55 and 56 causes the energization oi magnetizing coils '19 and 82 of the time limit i-elays/ and 14 and the consequent opening of "15 contacts 92 and 85.

The controller may now be moved to the second forward position thus engaging contact tlngers 65 with the controller segment-36. A circult is thereby established from the positive line 1 through conductor 30, contact fingers 64 and 65, o! the controller 10 bridged by the controller segment 36, conductor 63, conductor 28', contacts' 26, bridged by the interlock 27 on the directional contactor 3, conductor 25, contacts 110 and 111, conductor 113, actuating coil 11, and conductor 72 to the negative line 2. It will be noted that this-circuit immediately causes the short ,circuiting of the plugging resistor section 56. The plugging resistor section 56 is not 30 strictly a part of the starting resistor but is a resistor section having a rather high resistance value to prevent excessive current through the motor during plugging operation, as will be pointed out more in detail hereinafter.

85. I Since the energization oi. coil 11 established the short circuit for plugging resistor section 56 through conductor 75, contacts 76, bridged by bri n member 77 and conductor 57, the circuit through 78 and magnetizing coil '79 is 40. deenergized and the time limit relay 15 will close its contact 85 after a predetermined interval 01' time. After the lapse of this predetermined limit of time, a circuit is established from the energized conductor 63, conductor 133, contacts 121, bridged by bridging member 122, con-v ductor. 109, contacts 85 bridged by bridging member 86, conductor 8'7, actuating coil 12, and conductor 72 to the negative line 2. Energizetion of coil 12 establishes a short circuit for resister section by the j circuit through conductor 88, contacts 89, bridging member 90 and conductor 76. Similar to the deenergization of the magnetizing coil 79 previously discussed, magnetizing coil 82 is'now deenergized and the time- 65 :limit relay 14 will close its contact 92 after a predetermined interval 01' time.

, Mter the lapse of time for which the relay 14 has been set, a circuit is established from the energized conductor 109, through contacts 92,

bridged by bridging member 93, conductor 91,

actuating coil 13 and conductor '72 to the negative line 2. Energization of coil 13 causes a short circuiting oi the last resistor section 54 through the conductor 102, contacts 103, bridg- [ng member 104, and conductor 88. The motor is now running at full forward speed.

Assuming that it is desired to plug the motor while it is running at full forward speed, then the controller 10 is moved to the full reverse position and the directional contactor 4 is energiaed, closing the contacts 35, 100 and 97', associated with this contactor, and the contacts 58 of the line contactor 5 are closed. Because oi the inertia of the load, which is of considerable value in steel-mill equipment, and the inertia of the rotating armature, rotation of the armsture will continue in the same direction and the counter-electromotive force of the motor does not immediately diminish noichange sign. During the movement or the controller from the full-forward tothe full-reverse position contactor 3 and the coils 11, 12 and 13 are deenergized and all 01 the sections of the starting resistor are connected in series with the motor.

It is very desirable that the resistance in series with the motor during plugging be quite high to prevent excessive currents passing through the armature which might injure the motor. The plugging relay 108 accomplishes this desirable result. It will be noted that when directional contactor 4 closes during the plugging operation, the voltage impressed upon movable coil 61 of the polarized plugging relay 108, is still in the same direction and in consequence contact membars 110 and 111 remain closed until the resistance drop across the armature overbalances the counter-electromotive force. When this takes place, the voltage impressed on the armature terminals being reversed causes energization of coil 61 in a direction opposite to its previous energization. A circuit is thus established from the positive line 1 through conductor 30, contact fingers 64 and 65, conductor 63, contacts 35, bridged by the interlock 34 on directional contactor 4, conductor 33, contact members lil and 112, conductor 113, actuating coil 11 and conductor 72 to the negative line. By reason of the delay in the closing of contact members 111, 112 by the plugging relay 108 until the motor speed has substantially decreased to zero, the 10 coil 11 could not be energized to short circuit plugging resistor section 56. The plugging resistor section 56, having a relatively high ohmic value, thus remains connected in the armature circuit during deceleration of the motor thereby 115 preventing excessive currents through the armature during plugging operation.

Energization of coil 11 in addition to the shortcircuiting of the plugging resistor section 56, causes the closing of contact members 121 and the deenergization of the magnetizing coil 79. After a predetermined interval of time, depending upon the action of the neutralizing coil 19 and the adjustment of the spring associated with the time-limit relay 15, contact members 85 125 close and a circuit is established ior the actuating coil 12 which extends from the energized conductor 63, through conductor 133, contact members 121, bridging member 122, conductor 109, contact member 85, bridging member 86 of time-limit relay 15, conductor 87, actuating coil 12 and conductor 72 to the negative line 2. In a similar manner the coil 13 is energized and the last resistor section 54 is shunted and the motor then operates at full speed in the reverse direction.

It is understood, of course, that if it is desired to start initially in the reverse direction the controller is moved in the reverse direction from the first to the second reverse position, and the sequence 01 operation and the circuits established for the motor and the various elements of the control system are similar to the sequence oi operation of the circuit above described in cor.- nection with the controller movement in the forward direction.

When it is desired to limit the plugging operation to a definite time interval, the scheme shown in Fig. 2 is utilized. when the controller is in the of! position and the positive and negative lines are energized, a circuit is established from the positive line 1, through conductor 16, resistor 20, neutralizing coils 18 and 19 oi the time-limit relays 14 and Hand conductor.

21 to the negative line'2. Upon movement of the controller 10 to the first forward position a circuit is established from the positive line 1,

, through conductor 30, contact fingers 64 and 66,

bridged by the controller segment 36, conductor 41, actuating coil 42, of the directional contactor 3, conductors 28 and 29, actuating coil 40 oiline contactor 5, conductor 115, neutralizing circuit through conductor 78, magnetizing coil M U ,speed in a forward direction, and thatthe atcoil 116 of time-limit relay 114 and the conductor 21 to the negative line 2. The contactsasso ciated with the directional contactor 3 immediately close and the contact members of the line contactor 5 close, whereas the time-limit relay 114 does not operate since only the neutralizing coil 116 is energized.

A motor circuit is established by the operation of contactors 3 and 5 which is alike in every particular to the motor circuit traced in connection with the first forward position of the controller 10 for the modification shown in Fig.

1. Since, for this first forward controller position the starting resistor sections 54, and the plugging resistor 56 are in series with the series field winding 52 and the armature 46 of motor 6, the resistance drop across the resistor sections 55 and 56 causes the energization" of a Movement of the controller to the second forward position causes the bridging oi contactv members 64 and 651 by the controller segment 36 and a circuit is established which extends through conductor. '71, one junctiono! contacts 121, actuating coil 11, conductor '72, contacts '73,

bridged by bridging member 74 and conductors 117 and 118 to the negative line 2. Energization of ,coil 11 causes the immediate closing of the contact members associated with that particular -accelerating relay, and the plugging resistor section 56 is shunted by the conductor '75, contact member '76 bridgedby bridging member'T'I. The

circuit previously traced im the magnetizing coil '79 is thus deenergized and theftime-limit relay 15 is actuated to close its contacts after the lapse of a predetermined interval of time.

Attention is called to the fact that when coil 11 was energized, coil 120 of the time-limit relay 114 was also connected in that circuit, however, since coil 120 during this stage of operation is vin series with the discharge resistor 119, the time-limit relay 114 is not caused to operate and the contact members '73 remain closed.

After the lapse of the time interval, determined by the spring adjustment and theneutralizing coil 19 of time relay '15, a circuit is es-,

tablished 'from the energized conductor .71, through contact members 121, bridging meniber 122, conductor 84, contact members bridged by the bridging member 86, conductor 87; actu- ,ating coil 12 01 the second accelerating relay and conductor 118 to the negative line 2. It will be noted that upon operation of the, accelerating relay .having the coil 12, contact members 125 closed, thus shunting the circuit established through the contacts '73 of the time-limit relay 114. Actuating coil 11 thus may remain energized regardless of whether contact members '73 are closed or not;

Energization of coil 12 causes the shunting of the resistor section 55 and the consequent deenergization of the magnetizing coil 82 of the time-limit relay 14. After a predetermined interval of time depending upon the spring adjustment and the neutralizing coil of the time-limit relay 14, the contact members 92 are closed, establishing a circuit which may be traced from the energized conductor 84 through conductor 91, contact members 92 bridged by bridging member 93, conductor 94, actuating coil 13 and conductors 127 and 118 to the negative line 2. Energization of coil 13 immediately causes the shunting of the resistor section 54 by the circuit thrpugh conductor 102, contact members 103 and bridging member 104. Energization of coil 13 also causes the closing of contact members 129 therebyestablishing a circuit from the energized conductor'll through the magnetizing coil 120,

tendant' desires to plug the motor, then the movement of the controller from the "full speed forward position through the 011 position to the full speed reverse" position'interrupts the circuits i or the actuating coils of the accelerating relays and causes the opening of the contact members associated with the accelerating relays. Magnetizing coil 120 is thereby deenergized and a predetermined interval of time must elapse beforezcontact member-s73 close to complete the circuit for the actuating coil 11 of the accelerating relay associatedwith theplugging resistor 56.

circuit for a definite time interval, The time interval for which the time-limit relay 114 stands adiusted by means of its adjusting spring and the neutralizing coil 116 is, of course, so chosen Fig. 3 was provided.

, If the attendant; should move the controller from the full forward""position to the "otP position and hold the controller in the "or!" position for a short inter al of time and then plug the motor the actuating coil 11 may be energized immediately and shunt the plugging resistor section 56 and subject the motor to excessive current surges. To prevent such large currents from traversing the motor circuit the time-limit relay 114 is so designed that the residual magnetism will retain contacts '73open as long as the neutralizing coil 116 is not energized.

The plugging resistor section56 which has a high ohmic value is retained in the armature By this arrangement the attendant cannot shorten the time interval of the plugging operation-since upon movement of the controller to the full reverse position neutralizing coil 116 will be energized and contacts 73 will not close prior to the lapse of time for which the timelimit. relay 114 has been adjusted.

In the modification shown in Fig. 3, a system of control is shown somewhat similar to the modification shown in Fig. 2, however, the motor will not come to rest if the control is moved from the full forward to the off" position and then to the full forward position but will immediateh accelerate to regain the full forward speed.

When lines 1 and 2 are energized and the controller is in the of! position. the neutralizing windings of the time-limit relays 14 and 15 are energized by a circuit similar to the circuit traced in connection with the modifications above discussed. Movement of the controller to the first forward" position causes operation of the directional contactor 3 and the line contactor 5 thereby establishing a motor circuit for the forward direction of operation corresponding in every particular to the corresponding circuit above discussed. However, during energization of the directional contactor 3 and the line contactor 5, a circuit is also established from the positive line 1 through conductor 30, contact fingers 64 and 66, bridged by the controller segment 36, conductor 41, neutralizing coil 31, of the reverse time-limit relay 8, magnetizing coils 62 of the forward time-limit relay 9, cohductors 132 and 29 and actuating coil to tire negative line'2. Establishment of this circuit causes the opening of contact members 73, however, the contacts 106 do not open since only the neutralizing coil 31 is energized. Since the resistor sections and 56 are in series with the motor circuit, time-limit relays 14 and 15 immediately operate to open contact members 92 and 85.

Upon movement of the controller to the second forward" position, contact fingers 64 and 65 are bridged by the controller segment 36 and a circuit is completed through conductors 134 and 105, contact members 106, bridged by the bridging .member 107, conductor 25, contact members 26, bridged by the interlock 27 on the directional contactor 3, and conductors 28 and 71, actuating coil 11 of the first accelerating relay through conductors 72 to the negative line 2. The contact members associated with the first accelerating relay immediately close and the plugging resistor section 56 is shunted. Magnetizing coil 79 of the time-limit relay 15 is thereby deenergized, and after a predetermined interval of time depending both upon the spring adjustment and the neutralizing coil 19, of the time-limit relay 15, a circuit is established from the energized conductor 105 through conductor 133, contacts 121 bridged by the bridging member 122, conductor 109, contact members 85, bridged by the bridging member 86, conductor 87, the actuating coil 12 of the second accelerating relay and conductor 72 to the negative line 2. The shunting of resistor section 55 deenertive line 2, thereby short-circuiting the resistor section 54 by the circuit through conductor 102, contact members 103 and bridging member 104. Upon the shunting of resistor section 54 the motor accelerates to full forward speed.

Moyement of the controller to the full reverse position immediately causes the operation of directional contactor 4 and the deenergization of directional contactor 3 and forward time-limit relay 9. At the same time the magnetizing coil 61 of the reverse time-limit relay 8 is energized causing the opening of contacts 106. By this operation all of the resistor sections of the startling resistor 7 are connected in series in the motor circuit and excessive currents through the motor circuit are prevented. While the motor decelerates the forward timelimit relay 9 being deenergized closes its contacts after a predetermined interval of time, thus preventing the energization of coil 11 and the consequent shunting of plugging resistor section 56 prior to the lapse of time for which the forward time-limit relay 9 has been adjusted.

Attention is called to the fact that the advantageous functions discussed in connection with the operation of the time-limit relay 114 of the modification shown in Fig, 2, and of the plugging relay 108 of the modification shown in Fig. l, are also present. If the controllerbe moved from the full forward to the neutral position and then, after a slight hesitation at the neutral position, is moved to the full reverse" position an energizing circuit for the actuating coil 11 cannot be established prior to the lapse of the desired time, since contacts 106 are retained in open position by the residual magnetism of time-limit relay 8 during the pause in the off position. The energization of the actuating coil 11 during plugging operation is thus always controlled by the time constant of the the value and time of existence of the counterelectromotive force of the motor.

While the controller is in the of! position the neutralizing windings 18 and 19 of the timelimit relays 14 and 15 are energized. Movement of the controller to the first forward" position establishes a circuit from the positive line 1 through conductors 16 and 30, contact fingers 64 and 66, bridged by the connected controller segments 36 and 38, conductor 41, actuating coil 42, of the directional contactor 3, conductors 28 and 29, actuating coil 40 ofthe line contactor 5 to the negative line 2. A circuit is also established from the energized conductor 41, through conductor 22, magnetizing coil 23, conductors 24 and 175 to the energized conductor 29. Energization of the directional contactor 3 and the line contactor 5 establishes the motor circuit including all of the resistor sections of the starting resistor 7.

Connected across the armature terminals of the motor from the conductors 45 to 47"is a circuit through conductor 60, neutralizing coil 61 of reverse time-limit relay 8, a neutralizing coil 62 of the forward time-limit'relay 9 and the resistor 63. Energization of the neutralizing Movement of the controller to the second I forward position causes the bridging of contact fingers 64 and 65 by the controller. segment 36, thereby establishing a. circuit through the con ductors 134 and 28, contact members 26 bridged by the interlock 2'? on directional c'ontactor 3, conductor 25, contact members 106 bridged by the bridging member 107, conductors 105 and 71, actuating coil 11 of the first accelerating relay and conductor 72 to the, negative line 2. The

plugging resistor section 56 havingfthe relatively high resistance value is thereby ,shunted and contact members 121 are closed. The shunting 5 of theplugging resistor section 56 deenergizes magnetizing coil 79, and after a predetermined interval of time a circuit is established from the energizing conductor 134 through conductor 133,

contacts 121, bridging member'122, conductor 109, contactmembers 85 bridged by the bridging member 86, conductor 87, actuating, coil 12 lar to the sequence of operation just described for acceleration in the forward direction, except that during such operation directional contactor 4 is operated and reverse time-limit, relay '8 is operated to open contact members 106 while contact members 73 of the forward time-limit rrlay.

9 remain closed.

If the attendant plugs the motor, that is,

.moves the controller from full forward to full reverse position, directional contactor 4 immediately operates, while directional contactor 3 and the accelerating relays associated with the resistor sections 54, 55 and the plugging load and the rotating armature, energization of neutralizing coil 62 is reversed, and the armature of the forward time-limit relay 9 proceeds to descend. After a predetermined interval of time,'depending both upon the spring "adjustment and the neutralizing coil 62' of time-limit relay 9, contact members 73 close. {Wherrcontact members 73 close, actuating coil 11 fis energized to shunt the, plugging resistor section 56.

From the foregoing','it will .be apparent that the plugging resistor section j56 cannot be shunted prior'to the lapse of time requiredfor the motor to come to rest, plus the' time interval for which the time-limit relayl9 has been adjusted. If the attendant moves the controller from the full forward? position to the off position and then again to the forwardiposition, the actuating coil 11 is immediately energized upon operation of the directional contactor 3, since the neutralizing coil 61 assured that the contact meml ers 106 remained closed during such operation.

In the modification shown in Fig. 5, the neutralizating coils l8 and 19 of the time-limitrelays 14 and 15 are energizedwhile the controller is inthe off position, as was made clearduring the foregoing description. Moven'ient of. the controller to the first forward position causes the bridging of contact fingers 64, 65 and 66 by the controller segment 36. Two independent parallel circuits are thereby established for the line oontactor 5 and the directional contactor 3, and in consequence contact members 26, 43, 49 and 58 are closed. The closure of contact members 43, 49 and 58 establishes a motor circuit through the resistor sections 54, 55 and the plugging resistor 56. When the contact members 26 are actuated to establish a circuit from the positive line 1, throughconductors 16 and 22, magnetizing coil 23, conductors 24 and 25, contact members 26 closed by the interlock 2'7 on the" directional contactor 3, conductors 28 and 29 to the negative line 2. Energization of coil 23 immediately causes the opening of contacts 73, the resistance drop across the resistor sections 55 and 56 opens contacts and 92.

A circuit is also established which extends from one of the terminals of the motor6 through the conductors 45, 47 and 60, neutralizing coil 61, of the reverse time-limit relay 8 and neutralizing coil 62, of the forward time-limit relay 9 andresistor 63 back to the motor. As long as the motor rotates in a forward direction,

the magnetic effect of coils 62 and 23 is additive and contact members ,73 are held in open position. Movement of the controller to the .second forward position establishes a circuit from the positive. line 1, through conductors 16 and 30, contact fingers 64 and 68, bridged by the connected controller segments 36 and 38, conductor 71, actuating'coil 11 of the first accelerating relay, conductors '72 and 105, contact members 106 bridged by the bridging member 10?, conductor 25, contact members 26,

bridged by the interlock 2'7 and conductors 28 and 29 tothe negative line 2. It will be noted that this modification (see Fig. 5) is different in this particular circuit from any of the other modifications described, since the control of the energization of the actuating coil 11 is subject directly to manual control modified to some extent by the operation of the time-limit relays 8 and 9. In this particular modification the plugging resistor section 56, while "still of relatively high resistance value, functions as a conventional section of a starting resistor. I By holding the controller in the first forward position the motor may be accelerated to a predetermined speed depending upon the loadand the resistance value of the resistor sections 54, 55 and 56 combined.

the energization of coil 11- short-circuits plugging resistor section 56, thereby deenergizing magnetizing coil79 and after a predetermined" interval of time,' depending upon the adjustment of the time-limit relay 15, contacts 8,- close. However, the closing of these contacts cannot establish any circuit because contact.

Operation of the first accelerating relay by finger so is am ,not connected to the positive line 1. Movement of the controller to the "third forward" position causes the bridging of contact fingers 64 and 69 of the connected controller segments 36 and 38 and coil 12 is energized by a circuit through conductor 84, contacts 85, bridged by the bridging member 86, conductor 87, actuating coil 12 of the second accelerating relay, conductors '12 and 105, contacts 106,

bridging member 107, conductor 25, contacts 26, bridged by the interlock 27 on the directional contactor 3 and thence to the negative line 2 through conductors 28 and 29.

Energization ofactuating coil 12 causes the shunting of resistor section 55, deenergization ,of magnetizing coil 82, and the consequent closing of the contact members 92, after a predetroller to the fourth forward" position causes.

termined interval of time depending upon the adjustment of the-time-limit relay 14. The closing of contacts 92 does not necessarily estab lish a circuit for the actuating coil 13 of the third accelerating relay. Movement of the-conthe bridging of contact fingers 84 and 70, thereby establishing a circuit through'conductor 91,

contacts 92, bridged by the bridging member 93, conductor 94, actuating coil l3, conductors '12.-and 105, contact members 106,- bridged by the midging member 107, conductor 25, contact members 26, bridged by the interlock 2'! on the directional contactor 3, and thence to the negative line 2 through the conductors 28 and29. Operation of the third accelerating relw shunts resistor section 54 and the motor accelerates to full forward speed. Attention is called to the fact that in th modification shown in Fig. 5 acceleration either in the forward or the reverse direction need not necessarily take place subject both to manual and. automatic control. By rapid movement of. the controller 10. W. to the fourth forward position, contact fingers 88, 69 and 70 are immediately bridged by the controller segments in no case may the plugging operation take place at a more rapid rate than determined by the inertia of the load and the rotating armature and the time constant for which the timelimit relays 8 and 9 have been adjusted.

I do not wishto be restrictedw the specific structural details, arrangementiof 'p'artsor' circuit connections herein set forth, as various modifications thereof maybe eflected Without,

departing from the spirlt'and scope. of 'invention. .I desire, therefore, that only such limitationsshallbeimposedasare appended claims.

indicated in the Iclaim as myinvention:

1. In a control system'for a armature, directional contactors, a manually operable controller for determining the direction of rotation of the armature by control of the directional contactors, a plugging resistor section, means 1 for shunting'said resistor section, means operable after the lapse of predetermined intervals of time and responsive to the counter- '1 electromotive force of the motor for controlling reversing motor, including a source of power, a motor having an" the resistor shunting means, a plurality of starting resistor sections, and means for successively shunting said starting resistor sections at different predetermined intervals of-time.

' 2. In a control system for a reversing motor, including a source of power, a motor having an armature, directional contactors, a manually operable controller fordetermining the direction of rotation of the armature by control of the directional contactors, a plugging resistor section, means for shunting said plugging resistor section, means operable after deceleration of the motor and the lapse of a predetermined time interval for shunting the plugging resistor section, starting resistor sections for connection in the motor circuit, means for shunting said starting resistor sections, and time limit relays, said means for shunting said starting resistor sections being controlled by said manual controller and the time limit relays. I

3. In a control system for a reversing motor,

including asource of power, a motor having an armature and series field winding, a starting resistor having a plurality of sections, means for shunting said sections, directional contactors and a manually movable controller for determining thedirection of rotation of the motor by control of the directional contactors, in combination with a plugging resistor for connection in series with the armature and series field winding, shunting means for the plugging resistor, and means operable after the lapse of a predetermined interval of time after plugging of the motor for controlling the plugging resistor shunting means.

4. In a control system for a reversing motor, including a source of 'power a motor having an armature and series field winding, a starting resistor having a plurality of sections, means for shunting said sections, directional contactors, and a manually movable controller for determining the direction of rotation of the motor by control of the directional contactors, in combination with a plugging resistor for connection in series with the armature and series field winding, shunting means for the plugging resistor and means responsive to the counteroperationfor controlling the operation of the 1 plugging resistor shunting means.

5. In a control systemfor a reversing motor, including a source of power, a motor having an armature and series field winding, a starting resistor having a plurality of sections, means for shunting said sections, directional contactors and a manually movable controller for deter- ,mining the direction of rotation of the motor by control of the -.directional contactors, in comin series with the armature and series field bination with a plugging reslstorfor connection winding-shuntin'gzj means for the,l usld1 lre I definite time an'd'responsive to the counterelectromotive force of the motor during plugging -floperation for,controlling the operation of the "plugging resistor-shunting means.

Q 8. In aicontrol'i'system for: a reversing motor,

including a source-jot power; "a m'otor' having an armature and'series fieldwinding, a starting re sistor-havingl'a plurality of sections, means for sistor' and, means operableaiter' the flapse'of a:

shunting said sections, directional contactors mining the'direction of rotation of the motor by control of the directional contactors, in combination withi aplugging resistor for connection .and a manually movable controller for deterin series with the armature and series field winding, shunting means tor the plugging resistor and controlling means operableaiter the lapse of a predetermined minimum time interval ,and responsive to the counter-electromotive ij iorce of the motor during plugging operation for controlling, the operation of the plugging resistor shunting. means, said controlling means being subject to 'co'r'itr'ol-fof the manual controller after/the lapse 'ottanmgtime interval greater than said minimum predeterminedtime interval.

7. Ina control system fora reversing motor] including a source of power, a motor, a starting resistor having a plurality of sections, means for successively shunting the starting resistor after the lapse of difierent predetermined in-' tervals of time, directional contactors for determining the direction of rotation of the motor, and a manual controller for controlling the resistor shunting means; in combination with a plugging resistor, .means for shunting thepluggingresistor, and a pair of time-limit relays responsive to the counter-electromotive force oi! the motor and operable after the lapseof ad-i j including a source of power, a motor'having an justable inherent time constants of the relays forcontrolling the operation of the plugging resistor shunting means.- l l 8. In a control system for a reversing motor, including a source of power, a motor, a-plurality of starting resistor sections, a plugging resistor section having higher resistance than one of the starting resistor sections, means or shunting the plugging resistor. section' durin initial establishment of a circuit for the motor and source of power, means operable, after the lapse of a predetermined interval, of time for successively shunting the starting resistor secv tions, a manually operable controller, and means 40' responsive to the direction of rotation of the motor with reierence to the voltage impressed on the motor for controlling the time of operastantially definite intervals of time after the tion of the means for shunting the plugging resistor.

v9. In a control system for a reversing motor, including a source of power, a motor, directional contactors, a manually operable controller for eflecting the operation of the directional contactors, a plurality of, startingresistor sections,

a plugging resistor section having a higher resistance value than the resistance value or any one or the starting resistor'sections, means responsive to the counter-electromotive torce of the motor for shunting the pluggingresistor section, and means operable after the lapse of a predeterminedinterval of time for successively shunting the starting resistor sections at subshuntingof the plugging resistor section.

' 10. In a control system for a reversing motor, including" aplurality of starting resistor sections for connection in series with the ,moton-a plugging resistor section having a hlgherfresistoperation or, said b means rorcontrolling the plugging operation toance than any. one of; the starting resistor sec- 'tions, means operable after thelapse or ,prede- 1 termined time intervals for shunting the startingresistor sections, directional contactors for,

selecting the direction of rotation of themotor, a manually operable controller toreflecting the directional ,ccontactors, or

.f prevent excessive-currents in themotor circuit comprising a polarized plugging relay responsive to the counter-electro-motive' torceoithe motor to control the means for shunting the mining the direction of rotation of the motor by."control of the directional contactors, in com- 'binationfwith a plugging resistor for connection in series with the motor during pluggingoperation, shunting means for the plugging resis- \tor, and means'flresponsive to a predetermined counter electro-motive force of the motor and operable a predetermined interval of time after the predetermined ",counter-electrornotive force has been attained by the motor for controlling the shunting means for the plugging resistor during the plugging operation.

12. In a control system tor a reversing motor,

armature and held windings, a starting resistor having a plurality of sections, means operable after the lapse of predetermined intervals of time for shunting the starting resistors at predetermined intervals 01 time after energization of the motor armature, directional contactors,

in combination with aplugging resistor for connection in series with the motor during plugging operation, shuntilng means for theplugging' resistor, means responsive to the counter-electro-. motive force of the motor and operable a predetermined interval of time after the counter-= electromotive force has attained a predetermined value for controlling the shunting means for the plugging resistor during the'plugging operation, and a manually operable controller-for efiecting the operation of the directional contactors and for further controlling the shunt-- ing means for the plugging resistor and the starting resistor sections.

, 13. In a control system for a reversing motor, including a source of power, a motor having an armature and field windings, a starting resistor having a plurality of -sections,j means operable after the lapse of predetermined intervals of time for shunting the starting resistors at predetermined intervals of time after connecting said source of power to, the motor, directional contactors, in combination with a plugging resistor for connection in series with the motor during plugging operation, shunting means for the plugging resistor, a pair of relays one op-' erable to control the plugging resistor shunting means when the motor is plugged after forward operation'and the other operable to control the plugging resistor shunting means when the motor is plugged after reverse operation, said 'relays being responsive to the counter-electromotive'force of the motor and operable at prea determined, time intervals after the counterelectromotive force ,has attained a predetermined value, and a manually operable controller for selectively effecting the operation of the directional contactors and for further control 1 ling theshunting means tor the pluggingresistor and the starting resistor sections,

14. In acontrol system for a reversing motor, Q including a source of power, a motor having an armature and field windings, a starting resistor 15c vice provided with an armature for controlling the operation of the contactor, and a relay for controlling the contactor and having a main exciting coil and also having an auxiliary coil connected across the motor armature, said electric device being designed to'operate a definite time interval after the excitation of the auxiliary coil of said relay, connected across the motor armature, has decreased to a predetermined age applied to the motor, control means re- Q sponsive to the line voltage for controlling the operation of the resistor-shunting means for the plugging resistor, means responsive to the counter-electromotive force 01 the motor cooperating with the control means to retain the control means in the position to which it has been actuated by an application of line voltage to prevent the operation of the shunting means for the plugging resistor when the reversing means is actuated to cause a reversal in the application of the voltage of the motor, time-limit means for successively effecting the operation of the resistor starting means and means operable by the plugging resistor shunting means for controlling the time-limit means.

WILLARD G. COOK. 

